Forum Moderators: open
Trying to help my kid with his math work. Trying not to look too dumb here. Can one of you WebmasterWorld math wizards help us out?
Problem:
One number is 6 more than another. If the sum of the smaller number and 3 times the larger number is 34, find the two numbers.
One number is 6 more than another. If the sum of the smaller number and 3 times the larger number is 34, find the two numbers.
two equations, two unknowns:
x=y+6
y+3x=34
substitute for x in the second equation and solve for y.
substitute for y in the first equation and solve for x.
4 and 10?
you get an F for not showing your work!
phranque, i am Russian, i do it in my head :),
i had 5+ in math
Two equations given:
1) L=S+6
2) S+3xL=34
Using equation #1, substitute (S+6) for L in Equation #2:
S+3x(S+6)=34
Convert 3x(S+6) to 3xS + 3x6:
S+3xS+3x6=34
3x6=18:
4xS+18=34
Subtract 18 from both sides of the equation:
4xS=16
Divide both sides of the equation by 4:
S=4
If S=4, and L=S+6, then L must be 10:
Plug the numbers back into equation #2 to test it:
4+(3x10)=34
Jim
two equations, two unknowns:
x=y+6
y+3x=34substitute for x in the second equation and solve for y.
substitute for y in the first equation and solve for x.
Let me guess, PHP, SQL & Basic pro or just good at maths?!
phranque, i am Russian, i do it in my head :),i had 5+ in math
Let me guess, PHP, SQL & Basic pro or just good at maths?!
3x + (x - 6) = 34
>> Which simplifies to
4x - 6 = 34
>> move the 6 over (changing the sign)
4x = 34 + 6
>> Add
4x = 40
>> Dividing gives
x = 10
>> Find smaller number
y = x - 6
>> which gives
y = 4
>> Hence (after checking 3*10 + 1*4 = 34)
Larger number = 10
Smaller number = 4
34=3(x+6)+x; came up with the lower number first;
you get an F for not showing your work!
Maybe at school, but surely not in real life :)
Trying to help my kid with his math work.
One question an adult couldn't answer:
Some bloke works for 10 hours, and sleeps for 8. In it's simplest form, what fraction of the day does he work?
Another:
What is the young of a Kangaroo called?
I can't believe people don't know this stuff!
While I'm not sure how old a 5th grader is, older than that by the looks of the question,...
a typical 5th grader would be 10-11 years old.
and now that you mention it algebra isn't usually taught in 5th grade - that must be some school.
mention it algebra isn't usually taught in 5th grade
Particularly with double unknowns.
One question an adult couldn't answer:
Some bloke works for 10 hours, and sleeps for 8. In it's simplest form, what fraction of the day does he work?Another:
What is the young of a Kangaroo called?
On the other hand, if you lived in Australia and couldn't answer the 2nd question...
[edited by: LifeinAsia at 5:02 pm (utc) on Nov. 21, 2007]
algebra isn't usually taught in 5th grade - that must be some school
We got a recommendation spit out by a computer from school that we work on Geometry with our 5th grader. Okeedoke.
And yes, some of the homework my 5th grade has been bringing home looks a lot like Algebra. I think it's supposed to be "guess and check" but some of the kids are using variable substitution because it's quicker.
Its easy, and your kid will never have a problem solving a series of non-homogenous linear equations again.
Pick a comprehensive but syntactically simple language such as a BASIC derivative and teach the kid how to build simple apps, games, toys etc. As a childhood hobby it is very engaging and involving and has the side effects of high intellectual stimulation at very minimal ongoing investment compared to most hobbies.
